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Take the opportunity to ask students to think back to what they learnt about proteins, fats and carbohydrates in Chapter 4 The chemicals of life. ◆ You could ask students to bring in some food labels and use some of these to discuss with the class the nutrient contents of various foods. ◆ Activity 7.1 Testing foods for vitamin C, could be carried out. Once students have experience of the test, they can then plan and carry out an investigation as suggested in the instructions. Common misunderstandings and misconceptions ◆ ◆
Students may associate the term ‘diet’ with trying to lose weight. They may think that fats are entirely bad and not appreciate that they are essential nutrients. ◆ It is very common for students to think that one nutrient can ‘contain’ another – for example, they may say that vitamins supply you with protein. Homework ideas ◆ ◆ ◆
Coursebook questions 7.1 to 7.6 End-of-chapter questions 2, 5, 7 Make an illustrated leaflet about balanced diets (either one page in detail, or an outline plan for the whole leaflet) that could be placed in a doctor’s waiting room for patients to read. ◆ Worksheet 7.1 Essential amino acids ◆ Workbook exercise 7.1 Diet
Topic 2
Digestion, absorption and assimilation
Coursebook sections 7.2, 7.3, 7.4, 7.5 Teaching ideas This is, in reality, a large collection of topics. There are many different possible routes through, and which you choose will depend to a large extent to the previous experience and knowledge of your students. It is well worth using some kind of assessment to find out what they already know and understand before you begin these topics. It is very easy for them to ‘switch off ’ because they have covered it all before. If they have indeed covered much of this before, then it is important to try to ensure that everything you do has something new, fresh and challenging in it, to keep their interest. ◆
Digestion and the need for it is frequently completely misunderstood by students taking IGCSE examinations. A clear understanding of what digestion is, and why it is necessary, is fundamental to an understanding of the whole of the rest of this topic, so it is well worth taking time over. For example, you could use a cylindrical piece of modelling clay with a hole through its centre to show students how the digestive system is a tube that runs from one end of the body to the other, and that its contents are still in the ‘outside world’ and not actually inside the body. This is a difficult concept for many students but unless they understand it, digestion and absorption make no sense at all. You could also do something similar with a tube made from a piece of wire netting or other perforated material. Feed strings of popper beads inside the tube, and show how they need to be split apart into individual beads before they can get through the holes in the sides of the tube.
Original material © Cambridge University Press 2014 © Cambridge University Press 2014
IGCSE Biology
Chapter 7: Teaching ideas
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